1. Field of the Invention
The invention relates to apparatus for implanting devices in atrial appendages. The implanted devices may be used to filter or otherwise modify blood flow between the atrial appendage and an associated atrium of the heart to prevent thrombi from escaping from the atrial appendage into the body's blood circulation system. In particular the invention relates to apparatus for percutaneous delivery and implantation of such devices.
2. Description of the Related Art
There are a number of heart diseases (e.g., coronary artery disease, mitral valve disease) that have various adverse effects on a patient's heart. An adverse effect of certain cardiac diseases, such as mitral valve disease, is atrial (or auricular) fibrillation. Atrial fibrillation leads to depressed cardiac output. A high incidence of thromboembolic (i.e., blood clot particulate) phenomena is associated with atrial fibrillation, and the left atrial appendage (LAA) is frequently the source of the emboli (particulates).
Thrombi (i.e., blood clots) formation in the LAA may be due to stasis within the fibrillating and inadequately emptying LAA. Blood pooling in the atrial appendage is conducive to the formation of blood clots. Blood clots may accumulate, and build upon themselves. Small or large fragments of the blood clots may break off and propagate out from the atrial appendage into the atrium. The blood clot fragments can then enter the body's blood circulation and embolize distally into the blood stream.
Serious medical problems result from the migration of blood clot fragments from the atrial appendage into the body's blood stream. Blood from the left atrium and ventricle circulates to the heart muscle, the brain, and other body organs, supplying them with necessary oxygen and other nutrients. Emboli generated by blood clots formed in the left atrial appendage may block the arteries through which blood flows to a body organ. The blockage deprives the organ tissues of their normal blood flow and oxygen supply (ischemia), and depending on the body organ involved leads to ischemic events such as heart attacks (heart muscle ischemia) and strokes (brain tissue ischemia).
It is therefore important to find a means of preventing blood clots from forming in the left atrial appendage. It is also important to find a means to prevent fragments or emboli generated by any blood clots that may have formed in the atrial appendages, from propagating through the blood stream to the heart muscle, brain or other body organs.
Some recently proposed methods of treatment are directed toward implanting a plug-type device in an atrial appendage to occlude the flow of blood therefrom.
Another treatment method for avoiding thromboembolic events (e.g., heart attacks, strokes, and other ischemic events) involves filtering out harmful emboli from the blood flowing out of atrial appendages. Co-pending and co-owned U.S. patent application Ser. No. 09/428,008now U.S. Pat. No. 6,551,303; U.S. patent application Ser. No. 09/614,091, U.S. now U.S. Pat. No. 6,689,150; U.S. patent application Ser. No. 09/642,291, now U.S. Pat. No. 6,652,555; U.S. patent application Ser. No. 09/697,628, now U.S. Pat. No. 6,652,556; U.S. patent application Ser. No. 09/932,512, now published as U.S. Application No. 20020022860A1; U.S. patent application Ser. No. 09/960,749, now published as U.S. Application Publication No. 20020035374A1; and U.S. patent application Ser. No. 10/094,730, now published U.S. Application Publication No. 20030057156A1, all of which are hereby incorporated by reference in their entireties herein, describe filtering devices which may be implanted in an atrial appendage to filter the blood flow therefrom.
Common catheterization methods (including transseptal procedures) may be used to implant the devices in the atrial appendages. A narrow diameter catheter delivery tube is passed through the patient's vasculature to provide a conduit or pathway to the patient's atrial appendage. The implant devices generally have an elastic or compressible structure. This structure allows a device to be reversibly compacted to a small size that is suitable for insertion in the narrow diameter catheter delivery tube. A compacted device is attached to a guide wire or a push rod, and moved through the catheter delivery tube to a deployment position within the patient's heart cavity. Then by remote manipulation, the compacted device may be expanded in situ, and detached from the push rod or guide wire to serve as an atrial appendage implant.
The success of the atrial implant treatment procedure depends on the deployment of the implant device in an appropriate position and orientation (relative to the atrial appendage). To be effective the device must intercept all of the blood flow through the atrial appendage. For example, for a filter device implant to be successful, the device should be positioned and oriented so that all of the atrial appendage blood flow is directed through device filter elements, and so that there is no seepage around the device.
However, the percutaneous catheterization delivery techniques used for implant delivery (which often rely on operator dexterity) may not be sufficiently precise to place the device in a desirable orientation at the first attempt. Inadvertent movement or instability in the position or orientation of the device delivery catheter tube may make precise placement of an atrial appendage implant device difficult. Placing a device in a suitable deployment position with a desirable orientation may in some cases require repeated position probing or adjustment. Further, properly placed compacted devices, may during subsequent in situ expansion or detachment become dislodged or misoriented. Under some conditions, it may even be desirable to withdraw a delivered device.
Co-pending and co-owned U.S. patent application Ser. No. 09/932,512 describes a catheterization apparatus having a positioning device or guide, which enables position probing and readjustment of as-delivered implant device positions. Consideration is now being given to additional catheterization apparatus features to enable controlled recovery or repositioning of implanted devices.